In the manual or automatic application of paints to objects, a partial flow of the paint, which generally contains both solids and/or binding agents and solvents, is not applied to the object: This partial flow is termed “overspray” among experts.
Furthermore, the terms overspray, overspray particles or overspray solids are always understood in the sense of a disperse system, such as an emulsion or suspension or a combination of these. The overspray is captured by the air stream in the spray booth and supplied to a separation facility, so that the air can be returned, if applicable following suitable conditioning, to the coating booth again.
In installations with a greater paint consumption in particular, for example in installations for painting vehicle bodies, wet separation systems on the one hand or electrostatically operating dry separators on the other hand are preferably used in a known manner. In known wet separators a relatively large amount of energy is required to circulate the very large quantities of water required. The processing of the flushing water is cost-intensive due to the high use of chemicals that bind and detackify the paint and due to the paint sludge disposal. Furthermore, due to the intensive contact with the flushing water, the air takes up a lot of moisture, resulting in turn in a high energy consumption to process the air in recirculating air mode. In electrostatically operating dry separators the paint overspray must be removed continuously from the separating surfaces, which is usually associated with very elaborate structural measures and can accordingly be susceptible to malfunction. In addition, the energy outlay is relatively high in such separators.
As an alternative to these separation systems, it is known from DE 10 2011 108 631 A1, for example, to work with exchangeable one-way filter modules, which on reaching a limit loading with overspray are exchanged for unloaded filter modules and are disposed of or recycled if applicable. The processing and/or disposal of such filter modules can be more compatible in energy terms and also with regard to the required resources than the outlay with a wet separator or an electrostatically operating separation device.
Depending on the nature of the coating material, various types of overspray with different characteristics can be produced in a surface treatment installation and it appears that the filter effect and the absorption capacity of filter modules of the same construction type is different for various overspray types and not always optimal. When painting vehicle bodies, solvent-based paints, water-soluble paints, 2-component and/or multicomponent paints are used, for example, which have various characteristics that are found accordingly in the overspray produced in each case also.